Measurement of Damping due to Bolted Joints

The damping of a structure assembled from subsystems (a built-up structure) is commonly assumed to be due to frictional effects in the joints. This paper attempts to investigate this hypothesis. A built-up beam with 10 bolted links and a plate with 27 bolts were tested. The procedure was to measure the damping and then remove a link or a bolt and then to repeat the measurement and remove a further link or bolt. This continued until all the links or bolts were removed. If the hypothesis is correct an analysis of the data was expected to show a correlation between the number of bolts and the damping. No such simple correlation was evident. One possibility is that the effect of joint damping is smaller than the effect of other sources of damping such as material damping. Other possibilities are also discussed.Copyright © 2013 by ASME